Minority charge carrier lifetimes over 20 ms were achieved in float‐zoned, dislocation‐free, p‐type silicon doped with gallium. Effects of dopant species and density on lifetime were determined. Other growth‐parameter‐related effects on lifetime, including growth speed, crystal diameter, cooling rate, impurity control, and microdefect distributions were also studied. In 52 mm diameter crystals, lifetime τ ranged from 21.6 ms at doping concentration to 7.9 ms at , before dropping off to 0.5 ms near as Auger‐limit lifetimes are approached. We found that τ decreases significantly with increasing crystal cooling rate in swirl‐free crystals; τ increases with increasing crystal diameter (as the thermal gradient near the interface decreases), and τ is higher for swirl‐free crystals than for those containing such microdefects.